The present invention relates to a sharpener and more particularly pertains to a sharpener which is specially designed for sharpening crayons.
Available sharpeners in the marketplace are mostly electric or hand-operated sharpeners tailored for sharpening pencils only. As crayons are generally thicker and more brittle than pencils, ordinary sharpeners fail to sharpen crayons smoothly and satisfactorily. Crayons are easily broken while being sharpened. Even when crayons are sharpened without broken, the tips of which are likely to be too sharp and easily broken while in use. Ordinary sharpeners therefore cannot fit the requirements for sharpening crayons, thus causing inconvenience and wastage.
There are some sharpeners in the marketplace tailor-made for sharpening crayons only but they are usually of designs very different from those of pencil sharpeners. The existing crayon sharpeners are designed to have the apex of their housing forming a predetermined parabolic shape. A smooth curved surface along the writing end of a crayon is created by applying force manually to press the writing end to the apex of the parabolic housing. U.S. Pat. No. 4,991,299 is a typical example of such manual crayon sharpeners. In comparison with the sharpening method by using a blade in a conventional pencil sharpener, the manual method of the existing crayon sharpeners is difficult to use, especially by children, and it is not possible to adjust the curvature of the writing end to suit the different requirements of the crayon users. Further, by pressing the writing end of a crayon to form a smooth curved surface, the texture of the writing end will condense and it affects the coloring results.